2016 Salmonella Outbreak Linked to Alfalfa Sprouts

Introduction

CDC is collaborating with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella Reading and Salmonella Abony infections.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet, coordinated by CDC, is the national subtyping network of public health and food regulatory agency laboratories. PulseNet performs DNA fingerprinting on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.

Thirty people infected with the outbreak strains have been reported from nine states. Of those ill people, 24 were infected with Salmonella Reading, 1 was infected with Salmonella Abony, and 5 were infected with both.  A list of the states and the number of cases in each can be found on the Case Count Map page.

Illnesses started on dates ranging from May 21, 2016 to July 20, 2016. Ill people range in age from less than 1 year to 72, with a median age of 30. Fifty-three percent of ill people are female. Five ill people have been hospitalized, and no deaths have been reported.

This outbreak can be illustrated with a chart showing the number of people who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after July 12, 2016, might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Investigation of the Outbreak

Epidemiologic and traceback evidence available at this time indicate that alfalfa sprouts supplied by Sprouts Extraordinaire of Denver, Colorado are the likely source of this outbreak.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Of the 27 ill people who were interviewed, 17 (63%) reported eating or possibly eating alfalfa sprouts in the week before illness started. This proportion is significantly higher than results from a 2006 survey of healthy people, in which 3% reported eating sprouts on a sandwich in the week before they were interviewed. Ill people in the current outbreak reported eating raw alfalfa sprouts on sandwiches from several different restaurants.

Federal, state, and local health and regulatory officials performed a traceback investigation from five restaurants where ill people reported eating alfalfa sprouts. This investigation indicated that Sprouts Extraordinaire supplied alfalfa sprouts to all five of these locations.

On August 5, 2016, Sprouts Extraordinaire recalled its alfalfa sprout products from the market due to possible Salmonella contamination. These products were sold in boxes labeled “5-lb Living Alfalfa” and were distributed to Arkansas, Colorado, Kansas, Louisiana, New Mexico, Texas, Wisconsin, and Wyoming. CDC recommends that restaurants and other retailers do not sell or serve and consumers do not eat recalled alfalfa sprouts supplied by Sprouts Extraordinaire. Read the Advice to Retailers and Consumers.

This investigation is ongoing, and we will update the public when more information becomes available. CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill people and to interview those people about foods they ate before they got sick.